The receiver firstly detects the SAP, called index demodulation in this letter, and demodulates the \(M\) -ary modulated symbols in the active subcarriers. There have been several detection algorithms for OFDM-IM systems [1]}, [2]}. For low computational complexity, a power based detection algorithm can be employed, but it degrades the error performance of OFDM-IM. In [3]}, [4]}, it is known that the optimal maximum likelihood (ML) detection can be implemented with low complexity and thus it is preferred to employ the ML detection.
